ToF Sensor Intensity Measurement Using Correlation Plateau
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Solution Overview
Problem
Conventional Time-of-Flight (ToF) sensors face challenges in accurately determining the intensity of light reflected from objects, especially with semi-transparent objects causing unwanted reflections, and require depth measurements to generate grayscale images, which is inefficient and prone to systematic errors.
Innovation Solution
A method and apparatus using a ToF sensor with a light-intensity-independent correlation function that exhibits a plateau in a target measurement range, allowing the intensity value to be determined based on the output of photo-sensitive pixels without considering light intensity, using modulated light and a reference signal with specific duty cycles to adjust the measurement range and minimize reflective influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ToF sensors are used to measure light intensity, then depth information can be obtained, but the measurement is affected by unwanted reflections from semi-transparent objects and requires complex depth calculations to generate grayscale images
Solution Approach 1:
The patent extracts the light intensity measurement function from the depth measurement process. By using a correlation function that exhibits a plateau in the target measurement range, the system can directly obtain intensity values from the photo-sensitive pixel output without performing depth calculations, thereby separating intensity measurement from depth measurement operations
Solution Approach 2:
The patent introduces a correlation function as an intermediary between the received light and the measurement output. This correlation function, when convolved with the received signal, produces an output whose amplitude directly represents light intensity, eliminating the need for complex depth-based intensity calculation and filtering out unwanted reflections
2Measurement precision
If grayscale images are generated by integrating received light into charge buckets, then intensity information is obtained, but the process is affected by systematic errors and unwanted reflections
Solution Approach 1:
The patent employs a correlation-based measurement approach where the measured signal is convolved with a reference correlation function. This feedback mechanism allows the system to compare the received modulated light signal against a known reference pattern, enabling accurate intensity extraction while compensating for systematic errors and rejecting unwanted reflections that do not match the reference pattern
Solution Approach 2:
The patent changes the measurement parameter from direct charge integration to correlation amplitude measurement. By measuring the amplitude of the correlation function output rather than directly integrating charges, the system achieves more reliable intensity measurements that are insensitive to unwanted reflections and systematic errors affecting traditional integration methods
3Productivity
If depth measurements are performed to generate grayscale images, then intensity information can be derived, but the process is inefficient and time-consuming
Solution Approach 1:
The patent extracts the intensity measurement capability from the depth measurement process. By configuring the correlation function to exhibit a plateau in the target measurement range, the system can directly read intensity values from the correlation output amplitude without performing the full depth measurement and calculation pipeline, enabling independent and rapid intensity imaging
Solution Approach 2:
The patent prepares the correlation function in advance with a plateau characteristic in the target measurement range. This preliminary configuration of the correlation function allows the system to directly obtain intensity measurements from the correlation output without requiring subsequent depth calculation steps, significantly reducing the time needed for grayscale image generation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate intensity sensing of light reflected from objects without depth measurements, reducing systematic errors and allowing for more frequent grayscale image capture, while ignoring reflective influences from semi-transparent objects or displays.
Implementation Method 1
A conventional ToF camera measures distance by emitting near infrared light
Implementation Method 2
The number of electrons in the bucket directly indicates the amount of reflected light
Data Source
AI summary
A method for determining an intensity value representing an intensity of light reflected from an object in a scene is provided. The method includes performing a Time-of-Flight (ToF) measurement of the scene using a ToF sensor. A light-intensity-independent correlation function of a photo-sensitive pixel of the ToF sensor exhibits a plateau in a target measure-ment range for the ToF measurement. The object is located within the target measurement range. The method further includes determining the intensity value based on an output of the photo-sensitive pixel for the ToF measurement.